Service carrier frequency selecting method and apparatus

ABSTRACT

Embodiments of the disclosed technologies provide a carrier frequency selecting method and apparatus. The method comprises: determining, by UE, whether information of a service carrier frequency sent by a base station is received, wherein the service carrier frequency is the carrier frequency to carry traffic selected by the base station when a target cell carrying the UE is a multi-carrier cell; residing, by the UE, at a carrier frequency corresponding to the information for a service carrier frequency, if so; and, otherwise, residing, by the UE, at an original camped carrier frequency. With the embodiments of the disclosed technologies, the problem that a service carrier frequency selecting strategy in related techniques is to perform selection passively and lacks initiative is solved, and a technical basis for balancing loads on carrier frequencies carrying traffic is provided and further system efficiency is enhanced for an NB-IoT system, which is mainly to transmit small data.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent document is a continuation of and claims priority toInternational Patent Application No. PCT/CN2017/072270, filed on Jan.23, 2017, which claims the benefit of priority of Chinese PatentApplication No. 201610084117.1, filed on Feb. 6, 2016; Chinese PatentApplication No. 201610140659.6, filed on Mar. 11, 2016; Chinese PatentApplication No. 201610666760.5, filed on Aug. 12, 2016; and ChinesePatent Application No. 201610877947.X, filed on Sep. 30, 2016. Theentire contents of the before-mentioned patent applications areincorporated by reference as part of the disclosure of this document.

FIELD OF THE TECHNOLOGY

The patent document relates to the field of communication and, moreparticularly, to a carrier frequency selecting method and apparatus.

BACKGROUND

Machine to Machine (M2M) communication is an important issue in thestudy of 5^(th) Generation (5G) Mobile Communication Technology, and itis also an important application area for future wireless communication.In the M2M project, a research subproject of a Narrow Band-Internet ofThings (NB-IoT) is proposed for characteristics of low-cost,low-throughput terminals, for the purpose of providing a low-throughputwireless communication service for the low-cost terminals of the NB-IoTin the frequency band of 200 KHz.

In order to save air interface signaling and achieve fast access for UE,the NB-IoT introduces the following context suspension and resumemechanism: when User Equipment (UE) and a Mobility Management Entity(MME) complete uplink and downlink data transmission, the UE's bearercontext and AS context can be suspended on an evolved base station (eNB,also called eNodeB) side and the MME side by using a Radio ResourceControl (RRC) connection suspension mechanism; and, UU and S1 interfacesconnections of the UE are quickly restored by connecting the RRC to aresume process, if data transmission between the UE and the MME isrequired subsequently.

Taking into account the capacity of a single-carrier cell of the 200 KHzspectrum bandwidth is very small, access to a large number of NB-IoTterminal will inevitably suffer a limited capacity, and a simplestrategy to expand a capacity is to cover a same area with multiplecarrier frequencies. However, if each carrier serves as one cellindependently, there are the following two problems: 1) in a samecoverage area there are multiple cells of the same coverage, and toomany cells will cause unnecessary wireless quality measurement overhead;2) a broadcast channel and a synchronization channel need to beconfigured for each carrier, which wastes resources of the carrier.Therefore, it is necessary to introduce the following multi-carrier cellstrategy: a plurality of single carrier cells within a same eNodeB thatcover a same area are aggregated into a multi-carrier cell. The specificmanifestation is as follows: multiple carriers share one physical cellidentification and share a broadcast channel and a synchronizationchannel, and a traffic channel can be transmitted at a certain carrierwithin the cell, wherein a carrier carrying the broadcast channel andthe synchronization channel is called an Anchor Carrier while a carriernot carrying the broadcast channel or the synchronization channel iscalled a Non-Anchor carrier.

The current service carrier frequency selecting strategy proposed isthat the traffic for one UE is evenly distributed to different carrierfrequencies based on the UE's International Mobile SubscriberIdentification Numbers (IMSIs), or the traffic for one UE is dynamicallyscheduled at multiple carrier frequencies by using a frequency hoppingstrategy. However, there may be a load imbalance problem with evenlydistributing the traffic for one UE to multiple carrier frequenciesbased on the IMSIs and there may be a problem of UE frequency switchingwith dynamically scheduling the traffic for one UE on multiple carriers,which is also inefficient for an NB-IoT system mainly to transmit asmall amount of data.

At present, there has not been a solution to the problem that a servicecarrier frequency selecting strategy in related techniques is to performselection passively and lacks initiative.

SUMMARY

Embodiments of the disclosed technologies provide a carrier selectingmethod and apparatus so as to at least solve the problem that a servicecarrier frequency selecting strategy in related techniques is to performselection passively and lacks initiative.

According to an embodiment of the disclosed technologies, provided is acarrier frequency selecting method comprising: determining, by UE,whether information for a service carrier frequency sent by a basestation is received, wherein the service carrier frequency is thecarrier to carry a service traffic selected by the base station when atarget cell carrying the UE is a multi-carrier cell; residing, by theUE, at a carrier corresponding to the information of a service carrierfrequency, if the determination result is yes; and, otherwise, residing,by the UE, at an original camped carrier.

Alternatively, the determining, by UE, whether information for a servicecarrier frequency sent by a base station is received comprises:receiving, by the UE, an RRC connection setup message, an RRC connectionresume message, an RRC connection reestablishment message, or an RRCconnection reconfiguration message; determining, by the UE, whether theRRC connection setup message, the RRC connection resume message, the RRCconnection reestablishment message, or the RRC connectionreconfiguration message received carries the information for a servicecarrier frequency.

Alternatively, a subsequent flow of the UE is performed at the servicecarrier frequency if the UE determines that the information for aservice carrier frequency sent by a base station is received, and,otherwise, the subsequent flow of the UE is performed at a currentcarrier.

Alternatively, the subsequent flow of the UE comprises at least one ofthe following processes of the UE in a current connection mode: a datatransmission and reception process, signaling transmission and receptiontransceiver process and random access process.

Alternatively, a random access parameter broadcast by the cell is usedas a random access parameter of the service carrier frequency.

Alternatively, when a UE carried by a multi-carrier cell is switchedfrom a connection mode to an idle mode, a strategy for selecting acamped carrier for the UE is: when it is determined that an RRC releasemessage, an RRC connection suspension message, an RRC connection setupmessage, or an RRC connection resume message sent by a base station isreceived, wherein the RRC release message or the RRC connectionsuspension message carries the information for a service carrierfrequency, the UE operates at a carrier corresponding to the informationfor a service carrier frequency carried in the RRC release message orthe RRC connection suspension message; or when it is determined that anRRC release message, or an RRC connection suspension message, and/or anRRC connection setup message, and/or an RRC connection resume messagesent by a base station is received, wherein the RRC release messageand/or the RRC connection suspension message do not carry theinformation for a service carrier frequency but the RRC connection setupmessage or the RRC connection resume message carries the information fora service carrier frequency, the UE operates at a carrier correspondingto the information for a service carrier frequency carried in the RRCconnection setup message or the RRC connection resume message; or whenit is determined that an RRC release message, an RRC connectionsuspension message, and/or an RRC connection setup message, and/or anRRC connection resume message sent by a base station is received,wherein none of the RRC release message, the RRC connection suspensionmessage, and/or the RRC connection setup message, and/or the RRCconnection resume message carries the information for a service carrierfrequency, the UE operates at a carrier at which the UE operates in anidle mode last time.

Alternatively, before the UE receiving information for a service carrierfrequency sent by a base station, the method further comprises:transmitting, by the UE, information for a multi-carrier supportcapability of the UE to the base station, wherein the information for amulti-carrier support capability of the UE is used to indicate whetherthe UE supports a multi-carrier function.

Alternatively, the information for a multi-carrier support capability ofthe UE is carried by one of the following messages: an RRC connectionsetup request, RRC connection resume request, and RRC connectionreestablishment request.

Alternatively, the UE's supporting a multi-carrier function means thatthe UE allows accepting the information for a service carrier frequencyconfigured by the base station.

Alternatively, the UE receiving information for a service carrierfrequency sent by a base station comprises: receiving, by the UE,information for transmission power of a narrowband reference signal(NRS) of the service carrier frequency sent by the base station.

Alternatively, the receiving, by the UE, information for transmissionpower of a narrowband reference signal (NRS) of the service carrierfrequency sent by the base station comprises: receiving, by the UE, asystem information block (SIB), an RRC connection setup message, an RRCconnection resume message, an RRC connection reestablishment message, oran RRC connection reconfiguration message; and, acquiring, by the UE,the information for transmission power of a narrowband reference signal(NRS) of the service carrier frequency from the system information block(SIB), the RRC connection setup message, the RRC connection resumemessage, the RRC connection reestablishment message, or the RRCconnection reconfiguration message.

Alternatively, before the UE receiving information for a service carrierfrequency sent by a base station, the method further comprises:receiving, by the UE, information for transmission power of an NRS ofthe service carrier frequency sent by the base station with a systeminformation block (SIB). The information for transmission power of anNRS of the service carrier frequency provides Energy per ResourceElement of the NRS to be used by the UE to perform an RSRP measurementand/or path loss calculation when the UE is assigned to the servicecarrier frequency.

Alternatively, the method further comprises: The information fortransmission power of an NRS of the service carrier frequency ischaracterized by a deviation from power of an NRS of an Anchor carrier;or, information for transmission power of an NRS corresponding to theservice carrier frequency is characterized by an absolute value of thepower of the NRS of the service carrier frequency.

Alternatively, before the UE receiving information for a service carrierfrequency sent by a base station, the method further comprises:transmitting, by the UE, a narrowband reference signal received power(NRSRP) value to the base station, wherein the NRSRP value is a powervalue on a resource unit on an Anchor carrier carrying a narrowbandreference signal measured by the UE, or the power value on a resourceunit on an Anchor carrier carrying a narrowband reference signalmeasured by the UE plus a offset value, and is used for the base stationdetermining quality of downlink radio coverage of the UE.

Alternatively, the narrowband reference signal received power (NRSRP)value measured by the UE is carried with one of the following messages:an RRC connection setup request, RRC connection resume request, and RRCconnection reestablishment request.

Alternatively, the offset value is: a difference between the power of anNRS of a Non-Anchor carrier and the power of an NRS of an Anchorcarrier.

Alternatively, a method of determining a wireless coverage level of theUE at the Non-Anchor carrier when an initial physical random accesschannel (PRACH) of the UE is carried on a Non-Anchor carrier comprises:acquiring, by the UE, the wireless coverage level by comparing ameasured narrowband reference signal received power (NRSRP) value of theAnchor carrier plus the offset value with a wireless coverage levelthreshold, wherein, alternatively, the wireless coverage level thresholdis configured by a system information block.

Alternatively, the offset value may be: a difference between the powerof a narrowband reference signal (NRS) of a Non-Anchor carrier and thepower of an NRS of an Anchor carrier.

Alternatively, the initial physical random access channel (PRACH) of theUE's being carried on a Non-Anchor carrier is as an initial PRACHprocess, wherein the initial PRACH process refers to a PRACH procedureother than a PRACH process triggered by a physical downlink controlchannel (PDCCH) order.

According to another embodiment of the disclosed technologies, providedis another carrier selecting method, comprising: determining, by a basestation, whether a target cell carrying UE is a multi-carrier cell; ifthe determination result is yes, transmitting, by the base station,information for a service carrier frequency to the UE, wherein theservice carrier frequency is a carrier to carry traffic selected by thebase station for the UE.

Alternatively, before the determining, by a base station, whether atarget cell carrying UE is a multi-carrier cell, the method alsoincludes: receiving, by the base station, an RRC connection setuprequest, an RRC connection resume request, or an RRC connectionreestablishment request from the UE.

Alternatively, after the receiving, by the base station, an RRCconnection setup request, an RRC connection resume request, or an RRCconnection reestablishment request from the UE, the method alsoincludes: acquiring, by the base station, information for amulti-carrier support capability of the UE from the RRC connection setuprequest, the RRC connection resume request, or the RRC connectionreestablishment request received, wherein the information for amulti-carrier support capability of the UE is used to indicate whetherthe UE supports a multi-carrier function.

Alternatively, in a case where the information for a multi-carriersupport capability of the UE indicates that the UE supports amulti-carrier function, the method also comprises: selecting, by thebase station, a service carrier frequency of the multi-carrier cell forthe UE and configuring information for the service carrier frequency.

Alternatively, the transmitting, by the base station, information for aservice carrier frequency to the UE comprises: carrying, by the basestation, the information for a service carrier frequency in an RRCconnection setup message and transmitting it to the UE; or carrying, bythe base station, the information for a service carrier frequency in anRRC connection resume message and transmitting it to the UE; orcarrying, by the base station, the information for a service carrierfrequency in an RRC connection reestablishment message and transmittingit to the UE; or carrying, by the base station, the information for aservice carrier frequency carried in an RRC connection reconfigurationmessage and transmitting it to the UE.

Alternatively, the transmitting, by the base station, information for aservice carrier frequency to the UE also comprises: transmitting, by thebase station, information for transmission power of an NRS of theservice carrier frequency to the UE.

Alternatively, the transmitting, by the base station, information fortransmission power of an NRS of the service carrier frequency to the UEalso comprises: transmitting, by the base station, the information fortransmission power of an NRS of the service carrier frequency carried ina system information block (SIB) to the UE; or transmitting, by the basestation, the information for transmission power of an NRS of the servicecarrier frequency carried in an RRC connection setup message to the UE;or transmitting, by the base station, the information for transmissionpower of an NRS of the service carrier frequency carried in an RRCconnection resume message to the UE; or transmitting, by the basestation, the information for transmission power of an NRS of the servicecarrier frequency carried in an RRC connection reestablishment messageto the UE; or transmitting, by the base station, the information fortransmission power of an NRS of the service carrier frequency carried inan RRC connection reconfiguration message to the UE.

Alternatively, the method further comprises: the information fortransmission power of an NRS corresponding to the service carrierfrequency is characterized by a deviation from power of an NRS of anAnchor carrier; the information for transmission power of an NRScorresponding to the service carrier frequency is characterized by anabsolute value of the power of the NRS of the service carrier frequency.

Alternatively, in a case where the base station transmits informationfor a service carrier frequency to the UE, the base station performs asubsequent flow for the UE at the service carrier frequency; and,otherwise, the base station performs a subsequent flow for the UE at acurrent frequency.

Alternatively, the subsequent flow performed by the base station for theUE comprises at least one of the following processes of the UE in acurrent connection mode: a data transmission and reception process,signaling transmission and reception transceiver process and randomaccess process.

Alternatively, the method further comprises: broadcasting, by the basestation, a random access parameter to the UE, wherein the random accessparameter applies to all carrier frequencies within the cell.

Alternatively, the transmitting, by the base station, information for aservice carrier frequency to the UE comprises: transmitting, by the basestation, the information for a service carrier frequency carried in anRRC release message or an RRC connection suspension message to the UE,wherein the information for a service carrier frequency is informationcorresponding to a carrier carrying a broadcast channel.

Alternatively, after the receiving, by the base station, an RRCconnection setup request, an RRC connection resume request, or an RRCconnection reestablishment request from the UE, the method alsoincludes: acquiring, by the base station, a narrowband reference signalreceived power (NRSRP) value from the RRC connection setup request, theRRC connection resume request, or the RRC connection reestablishmentrequest received, wherein the NRSRP value represents a power value on aresource unit of the NRS received by the UE and is used by the basestation to determine quality of downlink radio coverage of the UE.

Alternatively, the method further comprises: determining, by the basestation, based on the NRSRP value at least one of: a wireless coveragelevel, uplink radio coverage level, downlink radio coverage level,physical layer retransmission number of times of uplink channel, andphysical layer retransmission number of times of downlink channel.

According to still another embodiment of the disclosed technologies,provided is a carrier selecting method comprising: determining, by UE,whether broadcast information of a multi-carrier cell carries a Pagingcarrier frequency list and/or a number of Paging carrier frequencies,wherein the Paging carrier frequency list includes a carrier frequencyfor carrying a Paging message, and the number of Paging carrierfrequencies is used to determine the Paging carrier frequency list; ifthe determination result is yes, selecting, by the UE, a carrierfrequency as a carrier frequency for receiving Paging and/or carryingtraffic in the Paging carrier frequency list according to apreconfigured rule.

Alternatively, the selecting, by the UE, a carrier frequency as acarrier frequency for receiving Paging and/or carrying traffic in thePaging carrier frequency list according to a preconfigured rulecomprises: acquiring, by the UE, according to the preconfigured rule acarrier frequency index corresponding to the carrier frequency forreceiving Paging and/or carrying traffic; and, determining a carrierfrequency for receiving Paging and/or carrying traffic according to thecarrier frequency index.

Alternatively, the acquiring, by the UE, according to the preconfiguredrule a carrier frequency index corresponding to the carrier frequencyfor receiving Paging and/or carrying traffic comprises: acquiring, bythe UE, the corresponding carrier frequency index according to anidentification of the UE and a mod operation of a number of carrierfrequencies carrying the Paging message.

According to still another embodiment of the disclosed technologies,provided is also a carrier frequency selecting method comprising:determining, by a base station, a Paging carrier frequency list and/or anumber of Paging carrier frequencies, wherein the Paging carrierfrequency list includes a carrier frequency for carrying a Pagingmessage, and the Paging carrier frequency list is used by user equipment(UE) to select a carrier frequency as a carrier frequency for receivingPaging and/or carrying traffic in the Paging carrier frequency listaccording to a preconfigured rule, and the number of Paging carrierfrequencies is used to determine the Paging carrier frequency list; and,carrying, by the base station, the Paging carrier frequency list and/orthe number of Paging carrier frequencies in broadcast information of amulti-carrier cell.

According to yet an embodiment of the disclosed technologies, providedis a carrier frequency selecting method comprising: acquiring, by UE, acarrier frequency for carrying Paging information and/or traffic througha PDCCH carrying Paging indication information; and, performing, by theUE, transmission of subsequent Paging information and/or a subsequentservice at the carrier frequency.

Alternatively, the acquiring, by UE, a carrier frequency for carryingPaging information and/or traffic through a PDCCH carrying Pagingindication information comprises: receiving, by the UE, a carrierfrequency list of carrier frequencies carrying Paging messageinformation and/or traffic in a multi-carrier cell through a broadcast;and, acquiring, by the UE, in a PDCCH indices of the carrier frequenciescarrying Paging information and/or traffic in the carrier frequencylist.

Alternatively, the acquiring, by the UE, in a PDCCH indices of thecarrier frequencies carrying Paging information and/or traffic in thecarrier frequency list comprises: acquiring, by the UE, through DownlinkControl Information (DCI), in the PDCCH the indices of the carrierfrequencies carrying Paging information and/or traffic in the carrierfrequency list.

According to yet an embodiment of the disclosed technologies, providedis also a carrier frequency selecting method comprising: determining, bya base station, a carrier carrying Paging information and/or traffic;and, indicating, by the base station, through a PDCCH carrying Pagingindication information, to UE a carrier carrying Paging informationand/or traffic, the carrier being used by the UE to perform transmissionof subsequent Paging information and/or a subsequent service at thecarrier.

Alternatively, the indicating, by the base station, through a PDCCHcarrying Paging indication information, to UE a carrier carrying Paginginformation and/or traffic comprises: transmitting, by the base station,to the UE a carrier frequency list of carrier frequencies carryingPaging message information and/or traffic in a multi-carrier cell in away of broadcast; and, carrying, by the base station, in a PDCCH indicesof the carrier frequencies carrying Paging information and/or traffic inthe carrier frequency list.

Alternatively, the carrying, by the base station, in a PDCCH indices ofthe carrier frequencies carrying Paging information and/or traffic inthe carrier frequency list comprises: carrying, by the base station,through DCI, in the PDCCH the indices of the carrier frequenciescarrying Paging information and/or traffic in the carrier frequencylist.

According to yet an embodiment of the disclosed technologies, providedis another carrier frequency selecting method comprising: determining,by UE, whether a service carrier frequency list is carried in broadcastinformation of a multi-carrier cell, wherein the service carrierfrequency list includes a carrier frequency for carrying traffic; and,if the determination result is yes, selecting, by the UE, a carrierfrequency as a carrier frequency at which the UE initiates trafficrequest in the service carrier frequency list according to apreconfigured rule.

Alternatively, the selecting, by the UE, a carrier frequency as acarrier frequency at which the UE initiates traffic request in theservice carrier frequency list according to a preconfigured rulecomprises: acquiring, by the UE, a carrier frequency index for a carrierfrequency at which the UE initiates traffic request according to thepreconfigured rule; and, determining a corresponding carrier frequencyat which the UE initiates traffic request according to the carrierfrequency index.

Alternatively, the acquiring, by the UE, a carrier frequency index for acarrier frequency at which the UE initiates traffic request according tothe preconfigured rule comprises: acquiring, by the UE, the carrierfrequency index according to an identification of the UE and a modoperation of a number of carrier frequencies at which the UE initiatestraffic request.

According to yet an embodiment of the disclosed technologies, providedis also another carrier frequency selecting method comprising:determining, by a base station, a service carrier frequency list,wherein the service carrier frequency list includes a carrier frequencyfor carrying traffic, and is used by UE to select a carrier frequency atwhich the UE initiates traffic request in the service carrier frequencylist according to a preconfigured rule; and, carrying, by the basestation, the service carrier frequency list in broadcast information ofa multi-carrier cell.

According to another embodiment of the disclosed technologies, providedis a carrier frequency selecting apparatus at UE, the carrier frequencyselecting apparatus comprising: a first determination module configuredto determine whether information for a service carrier frequency sent bya base station is received, wherein the service carrier frequency is thecarrier frequency to carry traffic selected by the base station when atarget cell carrying the UE is a multi-carrier cell; and, a moduleconfigured to operate at a carrier frequency corresponding to theinformation of a service carrier frequency when it is determined thatthe information for a service carrier frequency sent by a base stationis received to operate at an original camped carrier if it is determinedthat the information for a service carrier frequency sent by a basestation is not received.

According to another embodiment of the disclosed technologies, providedis another carrier frequency selecting apparatus at a base station, thecarrier frequency selecting apparatus comprising: a second determinationmodule configured to determine whether a target cell carrying UE is amulti-carrier cell; and, a first transmission module configured totransmit information for a service carrier frequency to the UE in a casewhere it is determined that the target cell carrying UE is amulti-carrier cell, wherein the service carrier frequency is a carrierfrequency to carry traffic selected by the base station for the UE.

According to still another embodiment of the disclosed technologies,provided is a carrier frequency selecting apparatus at UE, the carrierfrequency selecting apparatus comprising: a third determination moduleconfigured to determine whether broadcast information of a multi-carriercell carries a Paging carrier frequency list and/or a number of Pagingcarrier frequencies, wherein the Paging carrier frequency list includesa carrier frequency for carrying a Paging message, and the number ofPaging carrier frequencies is used to determine the Paging carrierfrequency list; and, a selection module configured to select a carrierfrequency as a carrier frequency for receiving Paging and/or carryingtraffic in the Paging carrier frequency list according to apreconfigured rule in a case where it is determined that the broadcastinformation of a multi-carrier cell carries a Paging carrier frequencylist and/or a number of Paging carrier frequencies.

According to still another embodiment of the disclosed technologies,provided is also a carrier frequency selecting apparatus at a basestation, the carrier frequency selecting apparatus comprising: a firstdeciding module configured to determine a Paging carrier frequency listand/or a number of Paging carrier frequencies, wherein the Pagingcarrier frequency list includes a carrier frequency for carrying aPaging message, and the Paging carrier frequency list is used by userequipment (UE) to select a carrier frequency as a carrier frequency forreceiving Paging and/or carrying traffic in the Paging carrier frequencylist according to a preconfigured rule, and the number of Paging carrierfrequencies is used to determine the Paging carrier frequency list; and,a second transmission module configured to carry the Paging carrierfrequency list and/or the number of Paging carrier frequencies inbroadcast information of a multi-carrier cell.

According to yet an embodiment of the disclosed technologies, providedis a carrier frequency selecting apparatus at UE, the carrier frequencyselecting apparatus comprising: an acquisition module configured toacquire a carrier frequency for carrying Paging information and/ortraffic through a PDCCH carrying Paging indication information; and, atransmission module configured to perform transmission of subsequentPaging information and/or a subsequent service at the carrier frequency.

According to yet an embodiment of the disclosed technologies, providedis also a carrier frequency selecting apparatus at a base station, thecarrier frequency selecting apparatus comprising: a second determinationmodule configured to determine a carrier frequency carrying Paginginformation and/or traffic; and, a third transmission module configuredto indicate, through a PDCCH carrying Paging indication information, toUE a carrier frequency carrying Paging information and/or traffic, thecarrier frequency being used by the UE to perform transmission ofsubsequent Paging information and/or a subsequent service at the carrierfrequency.

In accordance with the disclosed technologies, it is determined by UEwhether information for a service carrier frequency sent by a basestation is received, wherein the service carrier frequency is thecarrier frequency to carry traffic selected by the base station when atarget cell carrying the UE is a multi-carrier cell; the UE operates ata carrier frequency corresponding to the information for a servicecarrier frequency, if the determination result is yes; and, otherwise,the UE operates at an original camped carrier frequency. In this way,the problem that a service carrier frequency selecting strategy inrelated techniques is to perform selection passively and lacksinitiative is solved, and a technical basis for balancing loads oncarrier frequencies carrying traffic is provided and further systemefficiency is enhanced for an NB-IoT system, which is mainly to transmitsmall data.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are intended to provide a furtherunderstanding of the disclosed technologies and constitute a part of theapplication, and the illustrative embodiments of the describedtechniques and their descriptions are intended to explain thetechnologies and are not to be construed as limiting the invention. Inthe drawings:

FIG. 1 is a flow chart of a carrier frequency selecting method accordingto an embodiment of the disclosed technologies.

FIG. 2 is a structural block diagram illustrating a carrier frequencyselecting apparatus according to an embodiment of the disclosedtechnologies.

FIG. 3 is a flow chart of another carrier frequency selecting methodaccording to an embodiment of the disclosed technologies.

FIG. 4 is a structural block diagram illustrating another carrierfrequency selecting apparatus according to an embodiment of thedisclosed technologies.

FIG. 5 is a flow chart of still another carrier frequency selectingmethod according to an embodiment of the disclosed technologies.

FIG. 6 is a structural block diagram illustrating still another carrierfrequency selecting apparatus I according to an embodiment of thedisclosed technologies.

FIG. 7 is a flow chart of still another carrier frequency selectingmethod II according to an embodiment of the disclosed technologies.

FIG. 8 is a structural block diagram illustrating still another carrierfrequency selecting apparatus II according to an embodiment of thedisclosed technologies.

FIG. 9 is a flow chart of yet a carrier frequency selecting method Iaccording to an embodiment of the disclosed technologies.

FIG. 10 is a structural block diagram illustrating yet a carrierfrequency selecting apparatus I according to an embodiment of thedisclosed technologies.

FIG. 11 is a flow chart of yet a carrier frequency selecting method IIaccording to an embodiment of the disclosed technologies.

FIG. 12 is a structural block diagram illustrating yet a carrierfrequency selecting apparatus II according to an embodiment of thedisclosed technologies.

FIG. 13 is a flow chart of embodiment I of the disclosed technologies.

FIG. 14 is a flow chart of embodiment II of the disclosed technologies.

FIG. 15 is a flow chart of embodiment III of the disclosed technologies.

FIG. 16 is a flow chart of embodiment IV of the disclosed technologies.

FIG. 17 is a flow chart of embodiment V of the disclosed technologies.

FIG. 18 is a flow chart of embodiment VI of the disclosed technologies.

FIG. 19 is a flow chart of embodiment VII of the disclosed technologies.

FIG. 20 is a flow chart of embodiment VIII of the disclosedtechnologies.

FIG. 21 is a flow chart of embodiment IX of the disclosed technologies.

FIG. 22 is a flow chart of embodiment X of the disclosed technologies.

FIG. 23 is a flow chart of embodiment XI of the disclosed technologies.

FIG. 24 is a flow chart of embodiment XII of the disclosed technologies.

FIG. 25 is a flow chart of embodiment XIII of the disclosedtechnologies.

FIG. 26 is a flow chart of yet a carrier frequency selecting method IIIaccording to an embodiment of the disclosed technologies.

FIG. 27 is a flow chart of yet a carrier frequency selecting method IVaccording to an embodiment of the disclosed technologies.

EXAMPLE EMBODIMENTS

The disclosed technologies will be described hereinafter in detail withreference to the drawings and embodiments. It is to be noted thatembodiments in the present application and features in embodiments maybe combined with each other if no conflict is present.

It is to be noted that the terms in the description, claims and drawingsof the disclosed technologies, “first,” “second,” etc., are used todistinguish similar objects and are not necessary for describing aparticular order or succession.

In the present embodiment, provided is a carrier frequency selectingmethod. FIG. 1 is a flow chart of the carrier frequency selecting methodaccording to the embodiment of the disclosed technologies. As shown inFIG. 1, the process includes the following steps:

-   -   step S102: determining, by UE, whether information for a service        carrier frequency sent by a base station is received, wherein        the service carrier frequency is the carrier frequency to carry        traffic selected by the base station when a target cell carrying        the UE is a multi-carrier cell; and    -   step S104: operating, by the UE, at a carrier frequency        corresponding to the information for a service carrier        frequency, if the determination result is yes; and, otherwise,        operating, by the UE, at an original camped carrier frequency.

With the above steps, in a case where a target cell carrying UE is amulti-carrier cell, a base station selects a carrier frequency to carrytraffic and transmits information for a service carrier frequency to UE.By receiving the information for a service carrier frequency, the UEselects a corresponding service carrier frequency to perform datatransmission and reception. And, if the UE has not received informationfor a service carrier frequency, the UE operates at an original campedcarrier frequency. Thereby, a carrier frequency at which the UE operatescan be a carrier frequency to carry traffic selected by the base stationactively. Thus, the problem that a service carrier frequency selectingstrategy in related techniques is to perform selection passively andlacks initiative is solved, and a technical basis for balancing loads oncarrier frequencies carrying traffic is provided and further systemefficiency is enhanced for an NB-IoT system, which is mainly to transmitsmall data.

Alternatively, a base station described herein may be an evolved basestation (eNodeB).

As a preferred embodiment, the base station may transmit the informationfor a service carrier frequency with an RRC connection setup request, anRRC connection resume request, an RRC connection reestablishmentmessage, or an RRC connection reconfiguration message. In this case, inthe above step S102, an RRC connection setup message, an RRC connectionresume message (i.e., an RRC connection resume completion message), anRRC connection reestablishment message, or an RRC connectionreconfiguration message may be received, and then whether the RRCconnection setup message, the RRC connection resume message, the RRCconnection reestablishment message, or the RRC connectionreconfiguration message received carries the information for a servicecarrier frequency is determined.

As a preferred embodiment, a subsequent flow of the UE is performed atthe service carrier frequency if the UE determines that the informationfor a service carrier frequency sent by a base station is received; and,otherwise, the subsequent flow of the UE is performed at a currentcamped carrier frequency. Alternatively, the subsequent flow of the UEmay include all processes of the UE, such as a data reception andtransmission process, a signaling reception and transmission process,and a random process, in a current connection mode.

Alternatively, a random access parameter broadcast by the cell is usedas a random access parameter of the service carrier frequency.

Preferably, the UE may operate at a carrier frequency carrying abroadcast channel when the UE is currently in an IDLE state. Thespecific implementation may be as follows:

1. when performing initial selection in a cell, UE can monitor only acarrier frequency where a broadcast channel is, so it can only choose tooperate at the carrier frequency carrying the broadcast channel;

2. when performing reselection in the cell, implementation is madethrough a broadcast information configuration strategy; specifically, inconfiguration of broadcast information, an adjacent carrier frequency isbased on a carrier frequency carrying a broadcast channel; in this way,the UE will automatically reselect the carrier frequency carrying abroadcast channel when performing reselection;

3. when UE is switched from an RRC connection state to the IDLE mode, itis specified that the UE operates at a carrier frequency carrying abroadcast channel; the specific implementation is as follows:

In a case where it is determined in step S102 that an RRC releasemessage, or an RRC connection suspension message, and/or an RRCconnection setup message, and/or an RRC connection resume message sentby the base station are received, and the RRC release message or the RRCconnection suspension message carries the information for a servicecarrier frequency (also known as a redirecting information element), theinformation for a service carrier frequency is filled in withinformation corresponding to a carrier frequency carrying a broadcastchannel, so that the UE operates at the carrier frequency carrying abroadcast channel; if the RRC release message and/or the RRC connectionsuspension message do not carry the information for a service carrierfrequency (also known as a redirecting information element) but the RRCconnection setup message or the RRC connection resume message carriesthe information for a service carrier frequency (a redirectinginformation element), the UE operates at a carrier frequencycorresponding to the information for a service carrier frequency carriedin the RRC connection setup message or the RRC connection resumemessage; if none of the RRC release message, and/or the RRC connectionsuspension message, and/or the RRC connection setup message, and/or theRRC connection resume message carries the information for a servicecarrier frequency (also referred to as a redirect cell), the UEautomatically operates at a carrier frequency carrying a broadcastchannel and a synchronization channel of a current cell after release.

Specifically, when a UE carried by a multi-carrier cell is switched froma connection mode to an idle mode, a strategy for selecting a carrierfrequency for the UE is: when it is determined that an RRC releasemessage, or an RRC connection suspension message sent by the basestation is received, wherein the RRC release message or the RRCconnection suspension message carries the information for a servicecarrier frequency, the UE operates at a carrier frequency correspondingto the information for a service carrier frequency carried in the RRCrelease message or the RRC connection suspension message; or when it isdetermined that an RRC release message, or an RRC connection suspensionmessage, and/or an RRC connection setup message, and/or an RRCconnection resume message sent by a base station is received, whereinthe RRC release message and/or the RRC connection suspension message donot carry the information for a service carrier frequency but the RRCconnection setup message or the RRC connection resume message carriesthe information for a service carrier frequency, the UE operates at acarrier frequency corresponding to the information for a service carrierfrequency carried in the RRC connection setup message or the RRCconnection resume message; or when it is determined that an RRC releasemessage, or an RRC connection suspension message, and/or an RRCconnection setup message, and/or an RRC connection resume message sentby a base station is received, wherein none of the RRC release message,the RRC connection suspension message, and/or the RRC connection setupmessage, and/or the RRC connection resume message carries theinformation for a service carrier frequency, the UE operates at acarrier frequency at which the UE operates in an idle mode last time.

Alternatively, in a case where the UE determines that the informationfor a service carrier frequency sent by the base station is received,the UE receives information for transmission power of a narrowbandreference signal (NRS) of the service carrier frequency from the RRCconnection setup message, the RRC connection resume message, the RRCconnection reestablishment message, the RRC connection reconfigurationmessage, or the system information block (SIB). The information fortransmission power of a narrowband reference signal (NRS) of the servicecarrier frequency provides Energy Per Resource Element (EPRE) of the NRSto be used by the UE to: Reference Signal Received Power (RSRP)measurement, and/or, path loss calculation. The information fortransmission power of an NRS corresponding to the service carrierfrequency may be characterized by a deviation from power of an NRS of anAnchor carrier, or the information for transmission power of an NRScorresponding to the service carrier frequency may be characterized byan absolute value of the power of the NRS of the service carrierfrequency.

Further, a carrier frequency carrying a broadcast channel in a cell canbe acquired from SIB information or RRC signaling.

As a preferred embodiment, before the UE receives information for aservice carrier frequency sent by a base station, the UE may alsotransmit information for a multi-carrier support capability of the UE tothe base station, wherein the information for a multi-carrier supportcapability of the UE is used to indicate whether the UE supports amulti-carrier function. In the embodiment, the UE's supporting amulti-carrier function may mean that the UE allows accepting theinformation for a service carrier frequency configured by the basestation.

The information for a multi-carrier support capability of the UE may becarried by one of the following messages: an RRC connection setuprequest, RRC connection resume request, and RRC connectionreestablishment request.

Alternatively, before the UE determines that the information for aservice carrier frequency sent by the base station is received, the UEreceives information for transmission power of an NRS of the servicecarrier frequency through an SIB. The information for transmission powerof an NRS of the service carrier frequency provides Energy Per ResourceElement of the NRS to be used by the UE to perform an RSRP measurementand/or path loss calculation when the UE is assigned to the servicecarrier frequency. The information for transmission power of an NRScorresponding to the service carrier frequency may be characterized by adeviation from power of an NRS of an Anchor carrier, or the informationfor transmission power of an NRS corresponding to the service carrierfrequency may be characterized by an absolute value of the power of theNRS of the service carrier frequency.

Alternatively, before the UE initiates an initial PRACH process to thebase station, the UE is to determine a wireless coverage level where itis as follows:

when the UE operates on an Anchor carrier, the wireless coverage levelof the UE is acquired by comparing a narrowband reference signalreceived power (NRSRP) value of the Anchor carrier measured by the UEwith a wireless coverage level threshold; and

when the UE operates on a non-Anchor carrier, the wireless coveragelevel of the UE is acquired by comparing a narrowband reference signalreceived power (NRSRP) value of the Anchor carrier measured by the UEplus a offset value with a wireless coverage level threshold, whereinthe offset value may be a difference between the power of an NRS of aNon-Anchor carrier and the power of an NRS of an Anchor carrier.

A specific method of the UE determining its wireless coverage levelaccording to a type of a carrier at which the UE operates is as follows:for an initial PRACH process when the UE operates on an Anchor carrier,the UE obtains wireless coverage level NRSRP thresholds [threshold 0,threshold 1] after receiving a broadcast message; a wireless coveragelevel is decided by comparing the wireless coverage level NRSRPthresholds with a current NRSRP measurement as follows: the coveragethat the NRSRP value is greater than or equal to threshold 0 is ofcoverage level 0; the coverage that the NRSRP value is less thanthreshold 0 and is greater than or equal to threshold 1 is of coveragelevel 1; and, the coverage that the NRSRP value is less than threshold 1is of coverage level 2. For an initial PRACH process when the UEoperates on a Non-Anchor carrier, the UE obtains wireless coverage levelRSRP thresholds [threshold 0, threshold 1] after receiving a broadcastmessage; a wireless coverage level is decided by comparing the wirelesscoverage level RSRP thresholds with a current RSRP measurement plus a“deviation of power of an NRS of a Non-Anchor carrier from power of anNRS of an Anchor carrier;” the coverage that the RSRP measurement plusthe “deviation of power of an NRS of a Non-Anchor carrier from power ofan NRS of an Anchor carrier” is greater than or equal to threshold 0 isof coverage level 0; the coverage that the RSRP measurement plus the“deviation of power of an NRS of a Non-Anchor carrier from power of anNRS of an Anchor carrier” is less than threshold 0 and is greater thanor equal to threshold 1 is of coverage level 1; the coverage that theRSRP measurement plus the “deviation of power of an NRS of a Non-Anchorcarrier from power of an NRS of an Anchor carrier” is less thanthreshold 1 is of coverage level 2. The “deviation of power of an NRS ofa Non-Anchor carrier from power of an NRS of an Anchor carrier” added inthe above determination can be obtained based on information for powerof an NRS broadcasted in an SIB.

It will be apparent to those skilled in the art from the description ofthe above embodiments that the method according to the above embodimentscan be realized by means of software plus a necessary general hardwareplatform, or of course by means of hardware. But in many cases theformer is better implementation. Based on such understanding, thesubstantial part or the part making contribution over the prior art of atechnical solution may be embodied in the form of a software productthat is stored on a storage medium (such as a ROM/RAM, disk, and opticaldisc) including a number of instructions for causing a terminal device(which may be a mobile phone, a computer, a server, a network device, orthe like) to execute the methods of the various embodiments of thedisclosed technologies.

In the present embodiment, provided is a carrier frequency selectingapparatus at user equipment (UE). The apparatus is used to carry out theabove embodiments and preferred embodiments, and a description that hasbeen made will not be repeated. As used hereinafter, the term “module”may implement a combination of software and/or hardware of a predefinedfunction. Although the apparatus described in the following embodimentis preferably implemented by software, implementation by hardware or acombination of software and hardware is also possible and conceived.

FIG. 2 is a structural block diagram illustrating a carrier frequencyselecting apparatus according to the embodiment of the disclosedtechnologies. As shown in FIG. 2, the apparatus comprises: a firstdetermination module 22 configured to determine whether information fora service carrier frequency sent by a base station is received, whereinthe service carrier frequency is the carrier frequency to carry trafficselected by the base station when a target cell carrying the UE is amulti-carrier cell; and, a module 24 configured to operate at a carrierfrequency corresponding to the information of a service carrierfrequency when it is determined by first determination module 22 thatthe information for a service carrier frequency sent by a base stationis received or operate at an original camped carrier frequency if it isdetermined that the information for a service carrier frequency sent bya base station is not received.

In the present embodiment, provided is another carrier frequencyselecting method. FIG. 3 is a flow chart of another carrier frequencyselecting method according to the embodiment of the disclosedtechnologies. As shown in FIG. 3, the process includes the followingsteps:

-   -   step S302, in which a base station determines whether a target        cell carrying UE is a multi-carrier cell;    -   step S304, in which if the determination result is yes, the base        station transmits information for a service carrier frequency to        the UE, wherein the service carrier frequency is a carrier        frequency to carry traffic selected by the base station for the        UE.

With the above steps, a base station transmits information of a servicecarrier frequency to UE in a case where a target cell carrying the UE isa multi-carrier cell, wherein the service carrier frequency is a carrierfrequency to carry traffic selected by the base station for the UE.Thereby, the UE can select a corresponding carrier frequency to performdata transmission and reception by receiving the information for aservice carrier frequency, so that a carrier frequency at which the UEoperates may be a carrier frequency to carry traffic selected by thebase station actively. Thus, the problem that a service carrierfrequency selecting strategy in related techniques is to performselection passively and lacks initiative is solved, and a technicalbasis for balancing loads on carrier frequencies carrying traffic isprovided and further system efficiency is enhanced for an NB-IoT system,which is mainly to transmit small data.

As a preferred embodiment, the UE may send information for amulti-carrier cell support capability of the UE to the base stationthrough an RRC connection setup request, an RRC connection resumereconfiguration request, or an RRC connection reestablishment request.In this case, the base station receives the RRC connection setuprequest, the RRC connection resume request, or the RRC connectionreestablishment request from the UE before step S302. Alternatively, thebase station may carry the information for a service carrier frequencyin the RRC connection setup message and transmit it to the UE, or thebase station may carry the information for a service carrier frequencyin the RRC connection resume message and transmit it to the UE, or thebase station may carry the information for a service carrier frequencyin the RRC connection reestablishment message and transmit it to the UE,or the base station may carry the information for a service carrierfrequency carried in the RRC connection reconfiguration message andtransmit it to the UE.

Alternatively, the transmitting, by the base station, information for aservice carrier frequency to the UE comprises: transmitting, by the basestation, information for transmission power of an NRS of the servicecarrier frequency to the UE in a related message at the same time. Theinformation for transmission power of an NRS corresponding to theservice carrier frequency provides Energy Per Resource Element of theNRS to be used by the UE to perform an RSRP measurement and/or path losscalculation. The information for transmission power of an NRS of theservice carrier frequency may be characterized by a deviation from powerof an NRS of an Anchor carrier, or the information for transmissionpower of an NRS of the service carrier frequency may be characterized byan absolute value of the power of the NRS of the service carrierfrequency.

As a preferred embodiment, the base station may acquire information fora multi-carrier support capability of the UE from the RRC connectionsetup request, the RRC connection resume request, or the RRC connectionreestablishment request received, wherein the information for amulti-carrier support capability of the UE is used to indicate whetherthe UE supports a multi-carrier function. In the present embodiment, ina case where information for a multi-carrier support capability of theUE indicates that the UE supports a multi-carrier function, the basestation can select a service carrier frequency of a multi-carrier andconfigure information for the service carrier frequency for the UE thatsupports a multi-carrier function, and the UE that supports amulti-carrier function can accept the information for the servicecarrier frequency configured by the base station.

Preferably, the UE may operate at a carrier frequency carrying abroadcast channel when the UE is currently in an IDLE state. Thespecific implementation may be as follows:

1. when performing initial selection in a cell, UE can monitor only acarrier frequency where a broadcast channel is, so it can only choose tooperate at the carrier frequency carrying the broadcast channel;

2. when performing reselection in the cell, implementation is madethrough a broadcast information configuration strategy; specifically, inconfiguration of broadcast information, an adjacent carrier frequency isbased on a carrier frequency carrying a broadcast channel; in this way,the UE will automatically reselect the carrier frequency carrying abroadcast channel when performing reselection;

3. when UE is switched from an RRC connection state to the IDLE mode, itis specified that the UE operates at a carrier frequency carrying abroadcast channel; the specific implementation is as follows:

if the base station carries the information for the service carrierfrequency (also known as a redirecting information element) in an RRCrelease message or an RRC connection suspension message sent, theinformation for a service carrier frequency is filled in with onlyinformation corresponding to a carrier frequency carrying a broadcastchannel, so that the UE operates at the carrier frequency carrying abroadcast channel; if the base station does not carry the informationfor the service carrier frequency (a redirecting information element) inan RRC release message or an RRC connection suspension message, the UEautomatically operates at a carrier frequency carrying a broadcastchannel and a synchronization channel of a current cell after release.

Specifically, information for a carrier frequency carrying a broadcastchannel may be carried in an RRC release message or an RRC connectionsuspension message to guide the UE to operate at the carrier frequencycarrying a broadcast channel; or, information for a carrier frequencycarrying a broadcast channel is carried in an RRC connection setupmessage or an RRC resume completion message but the information for acarrier frequency carrying a broadcast channel is not carried in an RRCrelease message or an RRC connection suspension message, the UEautomatically operates at the carrier frequency carrying a broadcastchannel carried in the RRC connection setup or the RRC resume completionmessage when performing RRC release or RRC connection suspension; or,information for a carrier frequency carrying a broadcast channel is notcarried in an RRC connection setup message or an RRC resume completionmessage and the information for a carrier frequency carrying a broadcastchannel is not carried in an RRC release message or an RRC connectionsuspension message either, the UE automatically operates at a carrierfrequency at which the UE receives broadcast in an IDLE mode last timewhen performing RRC release or RRC connection suspension.

Further, a carrier frequency carrying a broadcast channel in a cell canbe acquired from SIB information or RRC signaling.

As a preferred embodiment, in a case where the base station transmitsinformation for a service carrier frequency to the UE, the base stationperforms a subsequent flow for the UE at the service carrier frequency;and, otherwise, the base station performs a subsequent flow for the UEat a current camped carrier. Alternatively, the subsequent flow that thebase station performs for the UE may include all processes of the UE,such as a data reception and transmission process, a signaling receptionand transmission process, and a random process, in a current connectionmode.

Alternatively, the method further comprises: transmitting, by the basestation, information for transmission power of an NRS of the servicecarrier frequency to the UE through a system message block (SIB), an RRCconnection setup message, an RRC connection resume message, an RRCconnection reestablishment message, or an RRC connection reconfigurationmessage. The information for transmission power of a narrowbandreference signal (NRS) of the service carrier frequency provides EnergyPer Resource Element of the NRS to be used by the UE to perform areference signal received power (RSRP) measurement and/or path losscalculation when the UE is assigned to the service carrier frequency.The information for transmission power of an NRS of the service carrierfrequency may be characterized by a deviation from power of an NRS of anAnchor frequency, or the information for transmission power of an NRS ofthe service carrier frequency may be characterized by an absolute valueof the power of the NRS of the service carrier frequency.

Alternatively, the base station may also broadcast a random accessparameter to the UE, wherein the random access parameter applies to allcarrier frequencies within the cell.

In the present embodiment, provided is another carrier frequencyselecting apparatus at a base station. FIG. 4 is a structural blockdiagram illustrating another carrier frequency selecting apparatusaccording to the embodiment of the disclosed technologies. As shown inFIG. 4, the apparatus comprises: a second determination module 42configured to determine whether a target cell carrying UE is amulti-carrier cell; and, a first transmission module 44 configured totransmit information for a service carrier frequency to the UE in a casewhere it is determined by the second determination module 42 that thetarget cell carrying UE is a multi-carrier cell, wherein the servicecarrier frequency is a carrier frequency to carry traffic selected bythe base station for the UE.

In the present embodiment, provided is a carrier frequency selectingmethod. FIG. 5 is a flow chart of the still another carrier frequencyselecting method according to the embodiment of the disclosedtechnologies. As shown in FIG. 5, the method comprises:

-   -   step S502, in which UE determines whether broadcast information        of a multi-carrier cell carries a Paging carrier frequency list        and/or a number of Paging carrier frequencies, wherein the        Paging carrier frequency list includes a carrier frequency for        carrying a Paging message, and the number of Paging carrier        frequencies is used to determine the Paging carrier frequency        list; and    -   step S504, in which if the determination result is yes, the UE        selects a carrier frequency as the carrier frequency for        receiving Paging and/or carrying traffic in the Paging carrier        frequency list according to a preconfigured rule.

With the above steps, a base station carries a Paging carrier frequencylist and/or a number of Paging carrier frequencies in broadcastinformation of a multi-carrier cell, wherein the number of Pagingcarrier frequencies is used to determine the Paging carrier frequencylist, and the Paging carrier frequency list includes a carrier frequencyfor carrying a Paging message, and the UE selects a carrier frequency asa carrier frequency for receiving Paging and/or carrying traffic in thePaging carrier frequency list according to a preconfigured rule, so thata carrier frequency for the UE may be a carrier frequency selected bythe base station actively. Thus, the problem that a service carrierfrequency selecting strategy in related techniques is to performselection passively and lacks initiative is solved, and a technicalbasis for balancing loads on carrier frequencies is provided and furthersystem efficiency is enhanced for an NB-IoT system, which is mainly totransmit small data.

As a preferred embodiment, a subsequent service flow may be performed onthe service carrier frequency specified in accordance with the abovemethod if UE receives the information specifying a service carrierfrequency given in the above embodiment, while a service carrierfrequency may be selected according to the preconfigured rule given inthe present embodiment and a subsequent service flow may be performed atthe service carrier frequency if the UE does not receive the informationspecifying a service carrier frequency given in the above embodiment.

There may be a plurality of preconfigured rules for UE selecting acarrier frequency in the above set of carrier frequencies, e.g.,obtaining a corresponding carrier frequency index based on anidentification (ID) of the UE and a mod operation of the number ofcarrier frequencies carrying a Paging message. That is, the UE mayacquire according to the preconfigured rule a carrier frequency indexcorresponding to the carrier frequency for receiving Paging and/orcarrying traffic, and determine a carrier frequency for receiving Pagingand/or carrying traffic according to the carrier frequency index. Thecarrier frequency index may be acquired by the UE based on anidentification (ID) of the UE and a mod operation of the number ofcarrier frequencies carrying a Paging message, or a carrier frequency ora carrier frequency index may also be acquired through other similarstrategy. The list of carrier frequencies carrying a Paging message mayalso be a list of all carrier frequencies of the multi-carrier cell,which means that all the carrier frequencies may carry a Paging message.

In an IDLE mode, UE can monitor a carrier carrying a broadcast channeland a carrier carrying its own Paging message in a way of frequencyhopping. Specifically, the UE monitors the carrier carrying its ownPaging message at a Paging Occasion and at a subsequent Paging messagereception phases, and at other times, the UE may monitor the carriercarrying a broadcast channel so as to receive system broadcast andmaintain synchronization with the network.

In the present embodiment, provided is a carrier frequency selectingapparatus at UE. FIG. 6 is a structural block diagram illustrating thestill another carrier frequency selecting apparatus I according to theembodiment of the disclosed technologies. As shown in FIG. 6, theapparatus comprises: a third determination module 62 configured todetermine whether broadcast information of a multi-carrier cell carriesa Paging carrier frequency list and/or a number of Paging carrierfrequencies, wherein the Paging carrier frequency list includes acarrier for carrying a Paging message, and the number of Paging carrierfrequencies is used by the UE to determine the Paging carrier frequencylist; and, a selection module 64 configured to select a carrierfrequency as a carrier frequency for receiving Paging and/or carryingtraffic in the Paging carrier frequency list according to apreconfigured rule in a case where it is determined by the thirddetermination module 62 that the broadcast information of amulti-carrier cell carries a Paging carrier frequency list and/or anumber of Paging carrier frequencies.

In the present embodiment, provided is a carrier frequency selectingmethod. FIG. 7 is a flow chart of the still another carrier frequencyselecting method II according to an embodiment of the disclosedtechnologies. As shown in FIG. 7, the method comprises:

-   -   step S702, in which a base station determines a Paging carrier        frequency list and/or a number of Paging carrier frequencies,        wherein the Paging carrier frequency list includes a carrier        frequency for carrying a Paging message, the Paging carrier        frequency list is used by UE to select a carrier frequency as a        carrier frequency for receiving Paging and/or carrying traffic        in the Paging carrier frequency list according to a        preconfigured rule, and the number of Paging carrier frequencies        is used to determine the Paging carrier frequency list; and    -   step S704, in which the base station carries the Paging carrier        frequency list and/or the number of Paging carrier frequencies        in broadcast information of a multi-carrier cell.

With the above steps, a base station carries a Paging carrier frequencylist and/or a number of Paging carrier frequencies in broadcastinformation of a multi-carrier cell, wherein the number of Pagingcarrier frequencies is used to determine the Paging carrier frequencylist, and the UE selects a carrier frequency as a carrier frequency forreceiving Paging and/or carrying traffic in the Paging carrier frequencylist according to a preconfigured rule, so that a carrier frequency forthe UE may be a carrier frequency selected by the base station actively.Thus, the problem that a service carrier frequency selecting strategy inrelated techniques is to perform selection passively and lacksinitiative is solved, and a technical basis for balancing loads oncarrier frequencies is provided and further system efficiency isenhanced for an NB-IoT system, which is mainly to transmit small data.

As a preferred embodiment, a subsequent service flow may be performed onthe service carrier frequency specified in accordance with the abovemethod if UE receives the information specifying a service carrierfrequency given in the above embodiment, while a service carrierfrequency may be selected according to the preconfigured rule given inthe present embodiment and a subsequent service flow may be performed atthe service carrier frequency if the UE does not receive the informationspecifying a service carrier frequency given in the above embodiment.

In the present embodiment, provided is a carrier frequency selectingapparatus at a base station. FIG. 8 is a structural block diagramillustrating the still another carrier frequency selecting apparatus IIaccording to the embodiment of the disclosed technologies. As shown inFIG. 8, the apparatus comprises: a first deciding module 82 configuredto determine a Paging carrier frequency list and/or a number of Pagingcarrier frequencies, wherein the Paging carrier frequency list includesa carrier frequency for carrying a Paging message, and the Pagingcarrier frequency list is used by UE to select a carrier frequency as acarrier frequency for receiving Paging and/or carrying traffic in thePaging carrier frequency list according to a preconfigured rule, and thenumber of Paging carrier frequencies is used by the UE to determine thePaging carrier frequency list; and, a second transmission module 84configured to carry the Paging carrier frequency list and/or the numberof Paging carrier frequencies in broadcast information of amulti-carrier cell.

In the present embodiment, provided is a carrier frequency selectingmethod. FIG. 9 is a flow chart of yet the carrier frequency selectingmethod I according to the embodiment of the disclosed technologies. Asshown in FIG. 9, the method comprises:

-   -   step S902, in which UE obtains a carrier frequency carrying        Paging information and/or traffic through a Physical Downlink        Control Channel (PDCCH) carrying Paging indication information;        and    -   step S904, in which the UE performs transmission of subsequent        Paging information and/or subsequent traffic at the carrier        frequency.

With the above steps, a base station carries a carrier frequencycarrying Paging information and/or traffic in a PDCCH carrying Pagingindication information, and UE obtains a carrier frequency carryingPaging information and/or traffic through the PDCCH carrying Pagingindication information and performs transmission of subsequent Paginginformation and/or a subsequent service, so that a carrier frequency forthe UE may be a carrier frequency selected by the base station actively.Thus, the problem that a service carrier frequency selecting strategy inrelated techniques is to perform selection passively and lacksinitiative is solved, and a technical basis for balancing loads oncarrier frequencies is provided and further system efficiency isenhanced for an NB-IoT system, which is mainly to transmit small data.

Considering that an amount of information that can be carried in thePDCCH is less, the UE can receive, through broadcast, a list of carrierfrequencies carrying Paging message information and/or traffic in amulti-carrier cell, and obtain in the PDCCH indices of the carrierfrequencies carrying Paging message information and/or traffic in thecarrier frequency list, thereby acquiring a corresponding carrierfrequency through a combination of the carrier frequency list and theindices.

Specifically, the UE may acquire, through DCI, in the PDCCH the indicesof the carrier frequencies carrying Paging information and/or traffic inthe carrier frequency list.

In the present embodiment, provided is a carrier frequency selectingapparatus at a base station. FIG. 10 is a structural block diagramillustrating yet the carrier frequency selecting apparatus I accordingto the embodiment of the disclosed technologies. As shown in FIG. 10,the apparatus comprises: an acquisition module 102 configured to acquirea carrier frequency for carrying Paging information and/or trafficthrough a PDCCH carrying Paging indication information; and, atransmission module 104 configured to perform transmission of subsequentPaging information and/or a subsequent service at the carrier frequency.

In the present embodiment, provided is a carrier frequency selectingmethod. FIG. 11 is a flow chart of yet the carrier frequency selectingmethod II according to the embodiment of the disclosed technologies. Asshown in FIG. 11, the method comprises:

-   -   step S1102, in which a base station determines a carrier        frequency carrying Paging information and/or traffic; and    -   step S1104, in which the base station indicates, through a PDCCH        carrying Paging indication information, to UE a carrier        frequency carrying Paging information and/or traffic, the        carrier frequency being used by the UE to perform transmission        of subsequent Paging information and/or subsequent traffic at        the carrier frequency.

With the above steps, a base station carries a carrier frequencycarrying Paging information and/or traffic in a PDCCH carrying Pagingindication information, and UE obtains a carrier frequency carryingPaging information and/or traffic through the PDCCH carrying Pagingindication information and performs transmission of subsequent Paginginformation and/or a subsequent service, so that a carrier frequency forthe UE may be a carrier frequency selected by the base station actively.Thus, the problem that a service carrier frequency selecting strategy inrelated techniques is to perform selection passively and lacksinitiative is solved, and a technical basis for balancing loads oncarrier frequencies is provided and further system efficiency isenhanced for an NB-IoT system, which is mainly to transmit small data.

Considering that an amount of information that can be carried in thePDCCH is less, the base station can transmit, through broadcast, a listof carrier frequencies carrying Paging message information and/ortraffic in a multi-carrier cell, and carry in the PDCCH indices of thecarrier frequencies carrying Paging message information and/or trafficin the carrier frequency list.

Specifically, the base station may carry, through DCI, in the PDCCH theindices of the carrier frequencies carrying Paging information and/ortraffic in the carrier frequency list.

In the present embodiment, provided is a carrier frequency selectingapparatus at a base station. FIG. 12 is a structural block diagramillustrating yet the carrier frequency selecting apparatus II accordingto the embodiment of the disclosed technologies. As shown in FIG. 12,the apparatus comprises: a second determination module 122 configured todetermine a carrier frequency carrying Paging information and/ortraffic; and, a third transmission module 124 configured to indicate,through a PDCCH carrying Paging indication information, to UE a carrierfrequency carrying Paging information and/or traffic, the carrierfrequency being used by the UE to perform transmission of subsequentPaging information and/or a subsequent service at the carrier frequency.

In the present embodiment, provided is a carrier frequency selectingmethod. FIG. 26 is a flow chart of yet the carrier frequency selectingmethod III according to the embodiment of the disclosed technologies. Asshown in FIG. 26, the method comprises:

-   -   step S2602, in which UE determines whether a service carrier        frequency list is carried in broadcast information of a        multi-carrier cell, wherein the service carrier frequency list        includes a carrier frequency for carrying traffic; and    -   step S2604, in which if the determination result is yes the UE        selects a carrier frequency as a service carrier frequency at        which the UE initiates a traffic request in the service carrier        frequency list according to a preconfigured rule.

With the above steps, a base station carries a service carrier frequencylist in broadcast information, and the UE selects a service carrierfrequency according to a predefined rule based on the service carrierfrequency list in the broadcast information and initiates trafficrequest when UE triggers traffic access request in a multi-carrier cell,so that a carrier frequency for the UE may be a carrier frequencyselected by the base station actively. Thus, the problem that a servicecarrier frequency selecting strategy in related techniques is to performselection passively and lacks initiative is solved, and a technicalbasis for balancing loads on carrier frequencies carrying traffic isprovided and further system efficiency is enhanced for an NB-IoT system,which is mainly to transmit small data.

As a preferred embodiment, a subsequent service flow may be performed onthe service carrier frequency specified in accordance with the abovemethod if UE receives the information specifying a service carrierfrequency given in the above embodiment, while a service carrierfrequency may be selected according to the preconfigured rule given inthe present embodiment and a subsequent service flow may be performed atthe service carrier frequency if the UE does not receive the informationspecifying a service carrier frequency given in the above embodiment.

Alternatively, the UE monitors a carrier frequency carrying a broadcastchannel and receives broadcast information, wherein the broadcastinformation carries a list of carrier frequencies that can carry trafficmessage. The UE selects one of the carrier frequencies as a carrierfrequency carrying traffic according to a pre-defined rule to initiate arandom access request and performs subsequent service transmission andreception at the carrier frequency. The predefined rule may be a methodof determining a service carrier frequency based on an ID of the UE anda mod operation of the number of service carrier frequencies, or thelike.

A specific method is as follows: in step S2604, the UE acquires acarrier frequency index for a carrier frequency at which the UEinitiates traffic request according to the preconfigured rule, anddetermines a corresponding carrier frequency at which the UE initiatestraffic request according to the carrier frequency index. Alternatively,the UE acquires the carrier frequency index according to an identity ofthe UE and a mod operation of a number of carrier frequencies at whichthe UE initiates traffic request.

In the present embodiment, provided is a carrier frequency selectingmethod. FIG. 27 is a flow chart of yet the carrier frequency selectingmethod IV according to the embodiment of the disclosed technologies. Asshown in FIG. 27, the method comprises:

-   -   step S2702, in which a base station determines a service carrier        frequency list, wherein the service carrier frequency list        includes a carrier frequency for carrying traffic, and is used        by UE to select a service carrier frequency at which the UE        initiates traffic request in the service carrier frequency list        according to a preconfigured rule; and    -   step S2704, in which the base station carries the service        carrier frequency list in broadcast information of a        multi-carrier cell.

As a preferred embodiment, a subsequent service flow may be performed onthe service carrier frequency specified in accordance with the abovemethod if UE receives the information specifying a service carrierfrequency given in the above embodiment, while a service carrierfrequency may be selected according to the preconfigured rule given inthe present embodiment and a subsequent service flow may be performed atthe service carrier frequency if the UE does not receive the informationspecifying a service carrier frequency given in the above embodiment.

The following description will be made with reference to preferredembodiments. The following preferred embodiments combine the aboveembodiments and preferred embodiments thereof. In following preferredembodiments, provided are a method and apparatus for load balancingbetween carrier frequencies in a multi-carrier cell. A specific strategyof the method is as follows:

When an eNodeB receives an RRC connection setup request or an RRCconnection resume request, the eNodeB selects a carrier frequencycarrying traffic in the multi-carrier cell according to a load situationin the multi-carrier cell, carries information for the carrier frequencyin an RRC connection setup message or an RRC connection resume messageand transmits it to the UE if a target cell carrying UE is amulti-carrier cell; and

After receiving the RRC connection setup message or the RRC connectionresume message, the UE performs data reception and transmission at theservice carrier frequency subsequently if information for a servicecarrier frequency is carried in the RRC connection setup message or theRRC connection resume message, while the UE performs subsequent servicereception and transmission at an original camped carrier frequency ifinformation for a service carrier frequency is not carried in the RRCconnection setup message or the RRC connection resume message.

Alternatively, UE's residing at a carrier frequency carrying a broadcastchannel in an IDLE mode is implemented as follows:

1. when performing initial selection in a cell, the UE can monitor onlya carrier frequency where a broadcast channel is, so it can only chooseto operate at the carrier frequency carrying the broadcast channel;

2. when performing reselection in the cell, implementation is madethrough a broadcast information configuration strategy; specifically, inconfiguration of broadcast information, an adjacent carrier frequency isbased on a carrier frequency carrying a broadcast channel; in this way,the UE will automatically reselect the carrier frequency carrying abroadcast channel when performing reselection;

3. when the UE is switched from an RRC connection state to the IDLEmode, it is specified that the UE operates at a carrier frequencycarrying a broadcast channel; the specific implementation is as follows:if an RRC release message or an RRC connection suspension messagecarries a redirecting information element, information for a carrierfrequency in the redirecting information element can be filled in withonly information corresponding to a carrier frequency carrying abroadcast channel, so that the UE operates at the carrier frequencycarrying a broadcast channel; and, if a redirecting information elementis not carried in an RRC release message or an RRC connection suspensionmessage, the UE automatically operates at a carrier frequency carrying abroadcast channel and a synchronization channel of a current cell afterrelease. Further, a carrier frequency carrying a broadcast channel in acell can be acquired from SIB information or RRC signaling.

With the above method, a technical problem that can be solved isproposing a method and apparatus for load balancing between carrierfrequencies in multi-carrier cell, which can achieve load balancingbetween the carrier frequencies in the multi-carrier cell.

The method and apparatus for load balancing between carrier frequenciesin a multi-carrier cell given in the present preferred embodiments willbe described in further detail with reference to the drawings.

In a following preferred embodiment, an example of a multi-carrier cellis provided. In the preferred embodiment, the multi-carrier cellincludes the following five carrier frequencies:

a first carrier that can serve as a carrier for an IDLE mode, and isprovided with a broadcast channel (PBCH), a synchronization channel(PSS/SSS), a cell reference channel (CRS), and a traffic channel(PDCCH/PDSCH); and,

second, third, fourth and fifth carrier frequencies that can only serveas carrier frequencies carrying traffic and are thus provided with onlya cell reference channel (CRS), and a traffic channel (PDCCH/PDSCH).

Embodiment I

FIG. 13 is a flow chart of embodiment I of the disclosed technologies.This embodiment explains a process of balancing loads between carrierfrequencies in a multi-carrier cell when an RRC connection isestablished.

Step 1301: UE transmits a random access preamble to carrier frequency 1of the multi-carrier cell.

Step 1302: carrier frequency 1 transmits a random access response to theUE.

Step 1303: the UE transmits an RRC connection setup request, whichincludes information for a multi-carrier support capability of the UEand/or an NRSRP value, to carrier frequency 1 of the multi-carrier cell.

Step 1304: a base station of the multi-carrier cell selects a servicecarrier frequency.

Step 1305: carrier frequency 1 transmits an RRC connection setupmessage, which includes that information for a service carrier frequencyis carrier frequency 2, to the UE.

Alternatively, the RRC connection setup message contains information fortransmission power of an NRS of carrier frequency 2, and the informationfor transmission power of an NRS of carrier frequency 2 may be anabsolute value (in the unit of dBm) of the transmission power of the NRSof carrier frequency 2, or a relative value (in the unit of dB or %) ofthe transmission power relative to transmission power of an Anchorcarrier (carrier frequency 1).

The information for transmission power of an NRS of carrier frequency 2provides Energy Per Resource Element of the NRS of carrier frequency 2to be used by the UE to perform an RSRP measurement and/or path losscalculation when the UE is assigned to carrier frequency 2.

Step 1306: carrier frequency 2 transmits uplink grant to the UE on thePDCCH.

Step 1307: the UE transmits an RRC connection setup completion messageto carrier frequency 2.

Step 1308: the UE performs uplink and downlink data transmission atcarrier frequency 2.

Embodiment II

FIG. 14 is a flow chart of embodiment II of the disclosed technologies.This embodiment explains a process of balancing loads between carrierfrequencies in a multi-carrier cell when an RRC connection is recovered.

Step 1401: UE transmits a random access preamble to carrier frequency 1of the multi-carrier cell.

Step 1402: carrier frequency 1 transmits a random access response to theUE.

Step 1403: the UE transmits an RRC connection resume request, whichincludes information for a multi-carrier support capability of the UEand/or an NRSRP value, to carrier frequency 1 of the multi-carrier cell.

Step 1404: a base station of the multi-carrier cell selects a servicecarrier frequency.

Step 1405: carrier frequency 1 transmits an RRC connection resumemessage, which includes that information for a service carrier frequencyis carrier frequency 2, to the UE.

Alternatively, the RRC connection resume message contains informationfor transmission power of an NRS of carrier frequency 2, and theinformation for transmission power of an NRS of carrier frequency 2 maybe an absolute value (in the unit of dBm) of the transmission power ofthe NRS of carrier frequency 2, or a relative value (in the unit of dBor %) of the transmission power relative to transmission power of anAnchor carrier (carrier frequency 1).

The information for transmission power of an NRS of carrier frequency 2provides Energy Per Resource Element of the NRS of carrier frequency 2to be used by the UE to perform an RSRP measurement and/or path losscalculation when the UE is assigned to carrier frequency 2.

Step 1406: carrier frequency 2 transmits uplink grant to the UE on thePDCCH.

Step 1407: the UE performs uplink and downlink data transmission atcarrier frequency 2.

Implementation where a message carrying information of a service carrierfrequency sent by a carrier to UE may also be an RRC connectionreestablishment message or an RRC connection reconfiguration message issimilar to those of embodiments I and II and thus will not repeatedherein.

Embodiment III

FIG. 15 is a flow chart of embodiment III of the disclosed technologies.This embodiment explains a process of balancing loads from other cell toa multi-carrier cell when an RRC connection is established.

Step 1501: UE transmits a random access preamble to carrier frequency 1of cell 1.

Step 1502: carrier frequency 1 of cell 1 transmits a random accessresponse to the UE.

Step 1503: the UE transmits an RRC connection setup request, whichincludes information for a multi-carrier support capability of the UEand/or an NRSRP value, to carrier frequency 1 of cell 1.

Step 1504: a base station of the multi-carrier cell balances the loads.

Step 1505: carrier frequency 1 of cell 1 transmits an RRC connectionsetup message, which includes information of a service carrier frequency(e.g., carrier frequency 2) and a physical cell identification of cell2, to the UE.

Alternatively, the connection setup message contains information fortransmission power of an NRS of carrier frequency 2, and the informationfor transmission power of an NRS of carrier frequency 2 is an absolutevalue (in the unit of dBm) of the transmission power of the NRS ofcarrier frequency 2.

The information for transmission power of an NRS of carrier frequency 2provides Energy Per Resource Element of the NRS of carrier frequency 2to be used by the UE to perform an RSRP measurement and/or path losscalculation when the UE is assigned to carrier frequency 2.

Step 1506: carrier frequency 2 of cell 2 transmits uplink grant to theUE on the PDCCH.

Step 1507: the UE performs uplink and downlink data transmission atcarrier frequency 2 of cell 2.

Embodiment IV

FIG. 16 is a flow chart of embodiment IV of the disclosed technologies.This embodiment explains a process of balancing loads from other cell toa multi-carrier cell when an RRC connection is recovered.

Step 1601: UE transmits a random access preamble to carrier frequency 1of cell 1.

Step 1602: carrier frequency 1 of cell 1 transmits a random accessresponse to the UE.

Step 1603: the UE transmits an RRC connection resume request, whichincludes information for a multi-carrier support capability of the UEand/or an NRSRP value, to carrier frequency 1 of cell 1.

Step 1604: a base station of the multi-carrier cell balances the loads.

Step 1605: carrier frequency 1 of cell 1 transmits an RRC connectionresume message, which includes information for a service carrierfrequency (e.g., carrier frequency 2) and a physical cell identificationof cell 2, to the UE.

Alternatively, the RRC connection resume message contains informationfor transmission power of an NRS of carrier frequency 2, and theinformation for transmission power of an NRS of carrier frequency 2 isan absolute value (in the unit of dBm) of the transmission power of theNRS of carrier frequency 2.

The information for transmission power of an NRS of carrier frequency 2provides Energy Per Resource Element of the NRS of carrier frequency 2to be used by the UE to perform an RSRP measurement and/or path losscalculation when the UE is assigned to carrier frequency 2.

Step 1606: carrier frequency 2 of cell 2 transmits uplink grant to theUE on the PDCCH.

Step 1607: the UE transmits an RRC connection setup completion messageto carrier frequency 2 of cell 2.

Step 1608: the UE performs uplink and downlink data transmission atcarrier frequency 2 of cell 2.

Implementation where a message carrying information for a servicecarrier frequency sent by a carrier to UE may also be an RRC connectionreestablishment message or an RRC connection reconfiguration message issimilar to those of embodiments I and II and thus will not repeatedherein.

Embodiment V

FIG. 17 is a flow chart of embodiment V of the disclosed technologies.This embodiment explains a process of balancing loads between carrierfrequencies in a multi-carrier cell when an RRC connection is to berecovered and an eNodeB cannot find context of UE and thus triggerssetup of an RRC connection.

Step 1701: UE transmits a random access preamble to carrier frequency 1of the multi-carrier cell.

Step 1702: carrier frequency 1 transmits a random access response to theUE.

Step 1703: the UE transmits an RRC connection setup request, whichincludes information for a multi-carrier support capability of the UEand/or an NRSRP value, to carrier frequency 1 of the multi-carrier cell.

Step 1704: a base station of the multi-carrier cell selects a servicecarrier frequency.

Step 1705: carrier frequency 1 transmits an RRC connection setupmessage, which includes that information of a service carrier frequency(carrier frequency 2), to the UE.

Alternatively, the RRC connection setup message contains information fortransmission power of an NRS of carrier frequency 2, and the informationfor transmission power of an NRS of carrier frequency 2 may be anabsolute value (in the unit of dBm) of the transmission power of the NRSof carrier frequency 2, or a relative value (in the unit of dB or %) ofthe transmission power relative to transmission power of an Anchorcarrier (carrier frequency 1).

The information for transmission power of an NRS of carrier frequency 2provides Energy Per Resource Element of the NRS of carrier frequency 2to be used by the UE to perform an RSRP measurement and/or path losscalculation when the UE is assigned to carrier frequency 2.

Step 1706: carrier frequency 2 transmits uplink grant to the UE on thePDCCH.

Step 1707: the UE transmits an RRC connection setup completion messageto carrier frequency 2.

Step 1708: the UE performs uplink and downlink data transmission atcarrier frequency 2.

Embodiment VI

FIG. 18 is a flow chart of embodiment VI of the disclosed technologies.This embodiment explains a process of balancing loads from carrierfrequencies in a multi-carrier cell to carrier frequencies in othermulti-carrier cell when an RRC connection is to be recovered and aneNodeB cannot find context of UE and thus triggers setup of an RRCconnection.

Step 1801: UE transmits a random access preamble to carrier frequency 1of cell 1.

Step 1802: carrier frequency 1 of cell 1 transmits a random accessresponse to the UE.

Step 1803: the UE transmits an RRC connection setup request, whichincludes information for a multi-carrier support capability of the UEand/or an NRSRP value, to carrier frequency 1 of cell 1.

Step 1804: a base station of the multi-carrier cell balances the loads.

Step 1805: carrier frequency 1 of cell 1 transmits an RRC connectionsetup message, which includes information of a service carrier frequency(e.g., carrier frequency 2) and a physical cell identification of cell2, to the UE.

Alternatively, the RRC connection setup message contains information fortransmission power of an NRS of carrier frequency 2, and the informationfor transmission power of an NRS of carrier frequency 2 may be anabsolute value (in the unit of dBm) of the transmission power of the NRSof carrier frequency 2.

The information for transmission power of an NRS of carrier frequency 2provides Energy Per Resource Element of the NRS of carrier frequency 2to be used by the UE to perform an RSRP measurement and/or path losscalculation when the UE is assigned to carrier frequency 2.

Step 1806: carrier frequency 2 of cell 2 transmits uplink grant to theUE on the PDCCH.

Step 1807: the UE transmits an RRC connection setup completion messageto carrier frequency 2 of cell 2.

Step 1808: the UE performs uplink and downlink data transmission atcarrier frequency 2 of cell 2.

Implementation where a message carrying information for a servicecarrier frequency sent by a carrier to UE may also be an RRC connectionreestablishment message or an RRC connection reconfiguration message issimilar to those of embodiments I and II and thus will not repeatedherein.

Embodiment VII

FIG. 19 is a flow chart of embodiment VII of the disclosed technologies.This embodiment explains a process that information for a carriercarrying a broadcast channel is carried in an RRC release message or anRRC connection suspension message to guide the UE to operate at thecarrier carrying a broadcast channel.

In step 1901, carrier frequency 2 transmits an RRC connection releasemessage or an RRC connection suspension message, which includesinformation for carrier frequency 1 carrying a broadcast channel, to theUE.

In step 1902, the UE enters an IDLE mode and operates at carrierfrequency 1.

Embodiment VIII

FIG. 20 is a flow chart of embodiment VIII of the disclosedtechnologies. This embodiment explains a process that information for acarrier carrying a broadcast channel is carried in an RRC connectionsetup message or an RRC resume completion message but the informationfor a carrier carrying a broadcast channel is not carried in an RRCrelease message or an RRC connection suspension message, the UEautomatically operates at the carrier carrying a broadcast channelcarried in the RRC connection setup or the RRC resume completion messagewhen performing RRC release or RRC connection suspension.

In step 2001, carrier frequency 2 transmits an RRC connection setupmessage or an RRC connection resume message, which includes informationfor carrier frequency 1 carrying a broadcast channel, to the UE.

In step 2002, carrier frequency 2 transmits an RRC connection releasemessage or an RRC connection suspension message, which does not includeinformation for carrier frequency 1 carrying a broadcast channel, to theUE.

In step 2003, the UE enters an IDLE mode and operates at carrierfrequency 1.

Embodiment IX

FIG. 21 is a flow chart of embodiment IX of the disclosed technologies.This embodiment explains a process that information for a carriercarrying a broadcast channel is not carried in an RRC connection setupmessage or an RRC resume completion message and the information for acarrier carrying a broadcast channel is not carried in an RRC releasemessage or an RRC connection suspension message either, the UEautomatically operates at a carrier at which the UE operates in an IDLEmode last time when performing RRC release or RRC connection suspension.

In step 2101, carrier frequency 1 transmits a broadcast message.

In step 2102, carrier frequency 2 and the UE perform uplink and downlinkdata transmission.

In step 2103, carrier frequency 2 transmits an RRC connection releasemessage or an RRC connection suspension message, which does not includeinformation for carrier frequency 1 carrying a broadcast channel, to theUE.

In step 2104, the UE enters an IDLE mode and operates at carrierfrequency 1.

Embodiment X

FIG. 22 is a flow chart of embodiment X of the disclosed technologies.This embodiment explains a process that UE carries a list of carrierfrequencies that can carry a Paging message in broadcast information ofa multi-carrier cell and selects one carrier frequency from the carrierfrequencies as a carrier for receiving a Paging message and/or carryingtraffic according to a predefined rule.

In step 2201, carrier frequency 1 transmits a broadcast message, whichcarries a list of carrier frequencies that can carry a Paging message,to UE 1;

In step 2202, carrier frequency 1 transmits a broadcast message, whichcarries a list of carrier frequencies that can carry a Paging message,to UE 2;

In step 2203, UE 1 determines according to the predefined rule thatcarrier frequency 2 is to carry Paging and service information of theUE, and the multi-carrier cell initiates Paging to UE 1 via carrierfrequency 2.

In step 2204, carrier frequency 2 and UE 1 perform data communication ina connection mode.

In step 2205, UE 2 determines according to the predefined rule thatcarrier frequency 3 is to carry Paging and service information of theUE, and the multi-carrier cell initiates Paging to UE 2 via carrierfrequency 3.

In step 2206, carrier frequency 3 and UE 2 perform data communication ina connection mode.

The predefined rule may be a strategy that a corresponding carrierfrequency index may be acquired based on an ID of the UE and a modoperation of the number of carrier frequencies carrying a Pagingmessage, or the like.

The list of carrier frequencies carrying a Paging message may also be alist of all carrier frequencies of the multi-carrier cell, which meansthat all the carrier frequencies may carry a Paging message.

In an IDLE mode, UE can monitor a carrier frequency carrying a broadcastchannel and a carrier frequency carrying its own Paging message in a wayof frequency hopping. Specifically, the UE monitors the carrierfrequency carrying its own Paging message at a Paging Occasion and at asubsequent Paging message reception phases, and at other times, the UEmonitors the carrier frequency carrying a broadcast channel so as toreceive system broadcast and maintain synchronization with the network.

Embodiment XI

FIG. 23 is a flow chart of embodiment XI of the disclosed technologies.This embodiment explains a process of transmitting a PDCCH carryingPaging indication information (e.g., P-TMSI) in a multi-carrier cell ata carrier frequency carrying a broadcast channel. The PDCCH carryingPaging indication information (e.g., P-TMSI) indicates a carrierfrequency carrying subsequent Paging information and/or a subsequentservice, and UE performs reception and transmission of subsequent Paginginformation and/or a subsequent service at the carrier frequencyindicated.

In step 2301, carrier frequency 1 transmits a PDCCH, which carriesPaging indication information to specify carrier frequency 2 as aservice carrier frequency for the UE, to UE 1.

In step 2302, carrier frequency 2 and UE 1 perform data communication ina connection mode.

In step 2303, carrier frequency 1 transmits a PDCCH, which carriesPaging indication information to specify carrier frequency 3 as aservice carrier frequency for the UE, to UE 2.

In step 2304, carrier frequency 3 and UE 2 perform data communication ina connection mode.

Embodiment XII

FIG. 24 is a flow chart of embodiment XII of the disclosed technologies.This embodiment explains a process of selecting a carrier when UEtriggers traffic access request in a multi-carrier cell.

In step 2401, UE 2 monitors carrier frequency 1 carrying a broadcastchannel and receives broadcast information, wherein the broadcastinformation carries a list of carrier frequencies that can carry serviceinformation.

In step 2402, UE 1 monitors carrier frequency 1 carrying a broadcastchannel and receives broadcast information, wherein the broadcastinformation carries a list of carrier frequencies that can carry serviceinformation.

In step 2403, UE 1 selects one of the carrier frequencies, carrierfrequency 2, as a carrier for service information according to apredefined rule so as to initiate a random access request (Msg1 PRACHPreamble).

In step 2404, UE1 performs subsequent data communication in a connectionmode at carrier frequency 2.

In step 2405, UE 2 selects one of the carrier frequencies, carrierfrequency 3, as a carrier frequency for service information according tothe predefined rule so as to initiate a random access request (Msg1PRACH Preamble).

In step 2406, UE 2 performs subsequent data communication in aconnection mode at carrier frequency 3.

The predefined rule may be a method of determining a service carrierfrequency based on an ID of the UE and a mod operation of the number ofservice carrier frequencies, or the like.

FIG. 25 is a flow chart of embodiment XIII of the disclosedtechnologies. This embodiment explains a method of an eNodeBtransmitting information for transmission power of an NRS of trafficcarrier to UE through a system message block.

In the present embodiment, the eNodeB transmits to the UE a broadcastmessage, which contains the following two information elements:

NRS transmission power to indicate transmission power of an NRS of anAnchor carrier; and

Non-Anchor carrier NRS transmission power to indicate transmission powerof an NRS of a Non-Anchor carrier.

The Non-Anchor carrier NRS transmission power may be an absolute valueof transmission power, for example, in the range of (−60 . . . 50) dBm.

The Non-Anchor carrier NRS transmission power may also be a relativevalue of the transmission power of an NRS of a Non-Anchor carrierrelative to the transmission power of an NRS of an Anchor carrier, forexample, in the range of (−30 . . . 30) dB or (0 . . . 100)%.

It is to be noted that each of the above modules may be implemented withsoftware or hardware. The latter may be implemented in a way that maybe, but is not limited to: all the above modules are located in a sameprocessor; or, the above modules are located in multiple processors,respectively.

An embodiment of the disclosed technologies also provides a storagemedium. Alternatively, in the present embodiment, the storage medium maybe configured to store program code for executing the following steps:

-   -   step S102, in which UE determines whether information of a        service carrier frequency sent by a base station is received,        wherein the service carrier frequency is the service carrier        frequency to carry traffic selected by the base station        according to a load situation when a target cell carrying the UE        is a multi-carrier cell; and    -   step S104, in which the UE resides at a service carrier        frequency corresponding to the information of a service carrier        frequency, if the determination result is yes; and, otherwise,        the UE operates at an original camped service carrier frequency.

Alternatively, the storage medium is further configured to store programcode for executing the following steps:

-   -   step S302, in which a base station determines whether a target        cell carrying UE is a multi-carrier cell; and    -   step S304, in which, if the determination result is yes, the        base station selects a carrier frequency carrying traffic        according to a load situation in the target cell and transmits        information for the carrier frequency selected to the UE.

Alternatively, the storage medium is further configured to store programcode for executing the following steps:

-   -   step S502, in which UE determines whether broadcast information        of a multi-carrier cell carries a Paging carrier frequency list        and/or a number of Paging carrier frequencies, wherein the        Paging carrier frequency list includes a carrier frequency for        carrying a Paging message, and the number of Paging carrier        frequencies is used to determine the Paging carrier frequency        list; and    -   step S504, in which, if the determination result is yes, the UE        selects a carrier frequency as a carrier frequency for receiving        Paging and/or carrying traffic in the Paging carrier frequency        list according to a preconfigured rule.

Alternatively, the storage medium is further configured to store programcode for executing the following steps:

-   -   step S702, in which a base station determines a Paging carrier        frequency list and/or a number of Paging carrier frequencies,        wherein the Paging carrier frequency list includes a carrier        frequency for carrying a Paging message, the Paging carrier        frequency list is used by user equipment (UE) to select a        carrier frequency as a carrier frequency for receiving Paging        and/or carrying traffic in the Paging carrier frequency list        according to a preconfigured rule, and the number of Paging        carrier frequencies is used to determine the Paging carrier        frequency list; and    -   step S704, in which the base station carries the Paging carrier        frequency list and/or the number of Paging carrier frequencies        in broadcast information of a multi-carrier cell.

Alternatively, the storage medium is further configured to store programcode for executing the following steps:

-   -   step S902, in which UE acquires a carrier frequency for carrying        Paging information and/or traffic through a PDCCH carrying        Paging indication information; and    -   step S904, in which the UE performs transmission of subsequent        Paging information and/or a subsequent service at the carrier        frequency.

Alternatively, the storage medium is further configured to store programcode for executing the following steps:

-   -   step S1102, in which a base station determines a carrier        frequency carrying Paging information and/or traffic    -   step S1104, in which the base station indicates, through a PDCCH        carrying Paging indication information, to UE a carrier        frequency carrying Paging information and/or traffic, the        carrier frequency being used by the UE to perform transmission        of subsequent Paging information and/or a subsequent service at        the carrier frequency.

Alternatively, the storage medium is further configured to store programcode for executing the following steps:

determining, by UE, whether a service carrier frequency list is carriedin broadcast information of a multi-carrier cell, wherein the servicecarrier frequency list includes a carrier frequency for carryingtraffic; and

if the determination result is yes, selecting, by the UE, a carrierfrequency as a carrier frequency at which the UE initiates trafficrequest in the service carrier frequency list according to apreconfigured rule.

Alternatively, the storage medium is further configured to store programcode for executing the following steps:

determining, by a base station, a service carrier frequency list,wherein the service carrier frequency list includes a carrier frequencyfor carrying traffic, and is used by UE to select a carrier frequency atwhich the UE initiates traffic request in the service carrier frequencylist according to a preconfigured rule; and

carrying, by the base station, the service carrier frequency list inbroadcast information of a multi-carrier cell.

Alternatively, in the present embodiment, the storage medium mayinclude, but is not limited to, a variety of media that can storeprogram code, such as a USB disk, a Read-Only Memory (ROM), a RandomAccess Memory (RAM), a mobile hard disk, a magnetic disc and a CD.

Alternatively, the examples described in the above embodiments andalternative embodiments may be referred to for a specific example in thepresent embodiment, which will not be described herein.

It will be apparent to those skilled in the art that the respectivemodules or steps of the disclosed technologies may be implemented with ageneral purpose computing device and may be concentrated in a singlecomputing device or distributed over a network composed of a pluralityof computing devices. Alternatively, they may be implemented withprogram code executable by a computing device, so that they may bestored in a storage device to be executed by the computing device and,in some cases, they may be implemented by executing the steps shown ordescribed in an order different from that described herein, or byseparately making them into individual integrated circuit modules, or bymaking a plurality of modules or steps of them into a single integratedcircuit module. Thus, the disclosed technologies are not limited to anyparticular combination of hardware and software.

The foregoing is only preferred embodiments of the disclosedtechnologies and is not for use in limiting the protection scopethereof, and for those skilled in the art, there may be variousmodifications and changes. Any modification, equivalent substitution,and improvement without departing from the spirit and principle of thedisclosed technologies should be covered in the protection scope of thispatent document.

INDUSTRIAL APPLICABILITY

As described above, a carrier frequency selecting method and apparatusprovided by embodiments of the disclosed technologies have the followingbeneficial effects: the problem that a service carrier frequencyselecting strategy in related techniques is to perform selectionpassively and lacks initiative is solved, and a technical basis forbalancing loads on carrier frequencies carrying traffic is provided andfurther system efficiency is enhanced for an NB-IoT system, which ismainly to transmit small data.

What is claimed is:
 1. A method for wireless communication, comprising:receiving, at a mobile device, a message from a base station, themessage including a carrier frequency list comprising a service carrierfrequency selected by the base station for carrying traffic; operatingthe mobile device at the service carrier frequency indicated by themessage, wherein the service carrier frequency is determined based on acarrier frequency index for the service carrier frequency; determining,by the mobile device, an energy per resource element of the narrowbandreference signal based on information for a transmission power of anarrowband reference signal of the service carrier frequency receivedfrom the base station; performing, by the mobile device, a referencesignal received power measurement based on the energy per resourceelement of the narrowband reference signal; and determining, by themobile device, a wireless coverage level of the mobile device bycomparing a measured reference signal received power with a referencevalue, wherein a deviation is selectively added to the measuredreference signal received power prior to the comparing depending onwhether the service carrier frequency is a non-anchor carrier.
 2. Themethod of claim 1, wherein the message includes a Radio Resource Control(RRC) connection setup, an RRC connection resume, an RRC connectionreestablishment, or an RRC connection reconfiguration.
 3. The method ofclaim 1, further comprising: performing a path loss calculation based onan energy per resource element of the narrowband reference signalprovided by the information for the transmission power.
 4. The method ofclaim 1, wherein the carrier frequency index is determined based on anidentification of the mobile device and a number of carrier frequenciescarrying a paging message.
 5. A method for wireless communication,comprising: transmitting, from a base station to a mobile device, amessage including a carrier frequency list comprising a service carrierfrequency selected by the base station for carrying traffic, wherein theservice carrier frequency is determined based on a carrier frequencyindex for the service carrier frequency; transmitting, from the basestation to the mobile device, information for a transmission power of anarrowb and reference signal of the service carrier frequency selectedby the base station to enable the mobile device to determine an energyper resource element of the narrowband reference signal and to perform areference signal received power measurement based on the transmissionpower such that a wireless coverage level of the mobile device isdetermined by comparing a measured reference signal received power witha reference value, wherein a deviation is selectively added to themeasured reference signal received power prior to the comparingdepending on whether the service carrier frequency is a non-anchorcarrier.
 6. The method of claim 5, wherein the message includes a RadioResource Control (RRC) connection setup message, an RRC connectionresume message, an RRC connection reestablishment message, or an RRCconnection reconfiguration message.
 7. The method of claim 5, whereinthe carrier frequency index is determined based on an identification ofthe mobile device and a number of carrier frequencies carrying a pagingmessage.
 8. An apparatus for wireless communication, comprising: areceiver configured to: receive a message from a base station, themessage including a carrier frequency list comprising a service carrierfrequency selected by the base station for carrying traffic, and aprocessor configured to: operate the apparatus at the service carrierfrequency indicated by the message, wherein the service carrierfrequency is determined based on a carrier frequency index for theservice carrier frequency; and determine an energy per resource elementof a narrowb and reference signal of the service carrier frequency basedon information for a transmission power of the narrowband referencesignal received from the base station; perform a reference signalreceived power measurement based on the energy per resource element ofthe narrowband reference signal; and determine a wireless coverage levelby comparing a measured reference signal received power with a referencevalue, wherein a deviation is selectively added to the measuredreference signal received power prior to the comparing depending onwhether the service carrier frequency is a non-anchor carrier.
 9. Theapparatus of claim 8, wherein the message includes a Radio ResourceControl (RRC) connection setup, an RRC connection resume, an RRCconnection reestablishment, or an RRC connection reconfiguration. 10.The apparatus of claim 8, wherein the processor is further configured toperform a path loss calculation based on an energy per resource elementof the narrowband reference signal provided by the information for thetransmission power.
 11. The device of claim 8, wherein the carrierfrequency index is determined based on an identification of the mobiledevice and a number of carrier frequencies carrying a paging message.12. An apparatus for wireless communication, comprising: a processorconfigured to select a service carrier frequency for carrying traffic;and a transmitter configured to: transmit, to a mobile device, a messageincluding a carrier frequency list comprising the service carrierfrequency selected for carrying traffic, wherein the service carrierfrequency is determined based on a carrier frequency index for theservice carrier frequency; transmit, to the mobile device, informationfor a transmission power of a narrowband reference signal of the servicecarrier frequency selected by the base station to enable the mobiledevice to determine an energy per resource element of the narrowbandreference signal and to perform a reference signal received powermeasurement based on the transmission power such that a wirelesscoverage level of the mobile device is determined by comparing ameasured reference signal received power with a reference value, whereina deviation is selectively added to the measured reference signalreceived prior to the comparing depending on whether the service carrierfrequency is a non-anchor carrier.
 13. The apparatus of claim 12,wherein the message includes a Radio Resource Control (RRC) connectionsetup, an RRC connection resume, an RRC connection reestablishment, oran RRC connection reconfiguration.
 14. The device of claim 12, whereinthe carrier frequency index is determined based on an identification ofthe mobile device and a number of carrier frequencies carrying a pagingmessage.
 15. A non-transitory computer readable medium having codestored thereon, the code when executed by a processor, causing theprocessor to: receive, at a mobile device, a message from a basestation, the message including a carrier frequency list comprising aservice carrier frequency selected by the base station for carryingtraffic; operate the mobile device at the service carrier frequencyindicated by the message, wherein the service carrier frequency isdetermined based on a carrier frequency index for the service carrierfrequency; determine an energy per resource element of the narrowbandreference signal based on information for a transmission power of anarrowband reference signal of the service carrier frequency receivedfrom the base station; perform a reference signal received powermeasurement based on the energy per resource element of the narrowbandreference signal; and determine a wireless coverage level by comparing ameasured reference signal received power with a reference value, whereina deviation is selectively added to the measured reference signalreceived power prior to the comparing depending on whether the servicecarrier frequency is a non-anchor carrier.
 16. The non-transitorycomputer readable medium of claim 15, wherein the message includes aRadio Resource Control (RRC) connection setup, an RRC connection resume,an RRC connection reestablishment, or an RRC connection reconfiguration.17. The non-transitory computer readable medium of claim 15, wherein thecode, when executed by the processor, causes the processorto: perform apath loss calculation based on an energy per resource element of thenarrowband reference signal provided by the information for thetransmission power.
 18. The non-transitory computer readable medium ofclaim 15, wherein the carrier frequency index is determined based on anidentification of the mobile device and a number of carrier frequenciescarrying a paging message.
 19. A non-transitory computer readable mediumhaving code stored thereon, the code when executed by a processor,causing the processor to: transmit, from a base station to a mobiledevice, a message including a carrier frequency list comprising aservice carrier frequency selected by the base station for carryingtraffic, wherein the service carrier frequency is determined based on acarrier frequency index for the service carrier frequency; transmitting,from the base station to the mobile device, information for atransmission power of a narrowband reference signal of the servicecarrier frequency selected by the base station to enable the mobiledevice to determine an energy per resource element of the narrowbandreference signal and to perform a reference signal received powermeasurement based on the transmission power such that a wirelesscoverage level of the mobile device is determined by comparing ameasured reference signal received power with a reference value, whereina deviation is selectively added to the measured reference signalreceived power prior to the comparing depending on whether the servicecarrier frequency is a non-anchor carrier.
 20. The non-transitorycomputer readable medium of claim 19, wherein the message includes aRadio Resource Control (RRC) connection setup message, an RRC connectionresume message, an RRC connection reestablishment message, or an RRCconnection reconfiguration message.
 21. The non-transitory computerreadable medium of claim 19, wherein the carrier frequency index isdetermined based on an identification of the mobile device and a numberof carrier frequencies carrying a paging message.